Biotin and Pregnancy

~ April 2002 No.146 ~

The developing fetus relies entirely on the mother for all of its nutrients to grow and develop in utero. Expectant mothers are indeed eating for two. This makes it even more important that, in the period leading up to and during pregnancy and lactation, women take extra care to ensure they have proper nutrition. The evidence for the role of folic acid in the prevention of birth defects is now clear. In response U.S. health regulatory officials have widely publicized the need for women planning to become pregnant to increase their folic acid intake. Biotin may now be another vitamin women need to think about before and during pregnancy.

Biotin is a water-soluble vitamin, generally classified as a B-complex vitamin along with vitamin C, niacin, riboflavin, folacin, thiamine, pantothenate. Biotin is required by all living organisms; it is an essential nutrient. However, biotin can only be synthesized by bacteria, yeasts, molds, algae, and some plant species. In the body, biotin is attached at the active site of four important enzymes called carboxylases that are involved in a variety of metabolic pathways.

Approximately 50 % of pregnant women excrete a particular compound (3-hydroxyisovaleric acid or 3-HIA). 3-HIA is excreted in the urine when biotin status is low. A recent study showed that supplementing pregnant women with biotin (300 ug/day) reduced the excretion of 3-HIA, presumably improving their biotin status. It is not clear yet whether the increased urinary 3-HIA measured in these pregnant women reflects a true deficiency or just a change in the maternal metabolism during pregnancy.

In 1998 the Food and Nutrition Board of the Institute of Medicine in the United States concluded that there was insufficient scientific evidence to calculate and recommend daily intake (RDI) for biotin. Rather they set an adequate intake level (AI). The AI for biotin assumes that current average intakes of biotin (35 mcg to 60 mcg/day) are meeting the dietary requirement.

More research is needed before the role of biotin in pregnancy is fully understood. In the meantime, pregnant women should eat a balanced diet to ensure that they have sufficient body stores of essential nutrients to share with their developing fetus.